Synthesis and characterization of second-generation dialkylphenacylsulfonium salt photoinitiators

A new, simplified method for the synthesis of dialkylphenacylsulfonium salt cationic photoinitiators has been developed. This novel method was successfully used for the preparation of dialkylphenacylsulfonium salts bearing a wide variation in the length and structure of the alkyl chains as well as the light absorbing aryl ketone chromophores and the anions. Modification of the lengths of the alkyl chains permits the design of compatible photoinitiators for highly nonpolar monomers and oligomers such as epoxy functional silicones, epoxidized polybutadiene and vegetable oils. This article describes the synthesis and characterization of these photoinitiators.